1. Field of the Invention
The present invention relates to a technical field for measuring components in a sample by using antigen-antibody reaction or hybridization of nucleic acid, or for measuring fine objects such as cells, micro-organisms or chromosomes.
2. Related Background Art
Recent advancements in the technology for detection of minor components have played a great role for early diagnosis of various diseases or prognostic diagnosis in the field of clinical examinations. Since 1958, when a method of determining insulin with labeling of radioactive iodine was publicized by S. A. Berson, it has been possible to measure plasma protein such as IgE, IgG, CRP or micro-globulin, tumor marker such as AFP, CEA or CA19-9, hormones such as TSH or T.sub.3, blood drugs, virus such as HBV or HIV and its sample, nucleic acid such as DNA or RNA, and it has been possible to perform many sample processings by automatization.
For most of these biological minor components, an immunological method using antigen-antibody reaction or a method using nucleic acid--nucleic acid hybridization has been employed. Example of such analytical methods is that the antigen-antibody reaction or nucleic acid hybridization with the sample is carried out by fixing antigen, antibody or single chain nucleic acid bonding specifically with the sample as a probe onto solid phase surfaces such as particles, beads or walls in an accumulation portion. Antigen-antibody compound or double chain nucleic acid is detected to determine the sample, using a labeled substance having specific interaction carrying a labeling substance with high detection sensitivity such as enzyme, fluorescent material or luminescent material, for example, labeled antigen, labeled antibody or labeled nucleic acid.
FIG. 20 is a view showing an example of a conventional apparatus for making the above-mentioned measurement. An insoluble carrier 202 having a reagent fixed on the surface thereof is contained in a reaction bath 201, to accumulate a sample fluid therein, causing the reaction and making a reaction fluid 203. The reaction fluid 203 is passed through a fluid feed pipe 204 and a valve 205 to be once stored in a syringe-type pump 206. Next, the valve 205 is switched to feed the stored reaction fluid to an optical cell 207 which is in a measurement location. The optical cell 207 is illuminated from a light source 208, and the light passing through the reaction fluid is detected by a light receiving element 209, whereby the colorimetry for the coloration reaction or fluorometry in the reaction fluid is carried out. The reaction fluid after the measurement is discharged as a waste fluid.
On the other hand, an apparatus in which a number of fine particles such as cell particles or chromosomes contained in a particle suspended fluid such as a blood sample are separated one by one to flow away and individual particle is measured with an optical or electrical method, has been put to practical use as a flow cytometer or particle counter.
FIG. 21 is a view showing an example of a conventional flow cytometer. A sample fluid which is a particle suspended fluid, is contained in a test tube 220, while a sheath fluid composed of PH buffer and physiological salt fluid is contained in a sheath bottle 223. Each fluid is once stored in a syringe-type pump 222, 225, and each valve 221, 224 is switched to feed the fluid by applying a pressure to the stored fluid. The sample fluid is supplied to a sample nozzle 226, and the sheath fluid is supplied to the surroundings 227 around the sample nozzle 226. Owing to a sheath flow principle, the sample fluid is converged hydrodynamically while being surrounded by the sheath fluid, and particles in the sample fluid are separated one by one to flow through a flow portion 228. Light is directed to the flow of particles from a light source 229 to measure the fluorescent or scattered light emitted from particles illuminated by light receiving elements 230, 231. A number of particles are sequentially measured, and the analysis for the kind or property of particles is made using a statistical method on the basis of the output from the elements. It is necessary to flush a fluid feed passages with a cleaning fluid every time one sample is measured, and a cleaning mechanism (not shown) is provided therefor.